Many molds or dies include movable die parts adapted to define channels, holes, or other openings within articles molded in the mold. The mold or die parts reciprocate or otherwise move between each molding or casting cycle to permit release of the molded article. Upon occasion, an element of the mold or die part fails or wears so that the molded or cast article no longer conforms to its intended design, thus mandating the repair or replacement of the mold or die part, or one or more of the elements forming the mold or die part. Such failure or wear can mandate that the entire mold or die be removed from the molding or die casting machine for disassembly and repair.
Dies and methods for die-casting V-block engines are well-known, and have been the subject of a number of patents as shown by U.S. Pat. Nos. 3,165,796; 3,433,292; 3,596,708; 4,206,799; 4,981,168; 5,204,127; 5,338,171; 5,429,175; 5,551,864; 5,865,241; and 6,761,208.
For example, U.S. Pat. No. 5,865,241 (the '241 Patent), discloses a die for casting a V-block for an internal combustion engine on a casting machine having a stationary platen and a movable platen. The die disclosed by the '241 patent includes, in addition to a die part on the stationary platen, two additional die parts, a central movable die part and a movable die part is mounted on the movable platen of the die casting machine. The central movable die is mounted on the movable platen of the die casting machine. The central movable die part movably carries a pair of die parts (frequently referred to as “slides”) that are movable along axes that are generally perpendicular to the direction of movement of the movable platen, and a pair of cylinder-forming die parts that are movable at acute angles with respect to the direction of movement of the movable platen, along intersecting axes, so that the cylinder-forming die parts may be moved from retracted positions within the central movable die part to positions extending within the cavity formed by the die where they may be fitted with sleeves to form the cylinders of an internal combustion engine V-block when the cavity is filled with molten metal. After the cylinder-forming die parts are moved into their extended positions, a pair of double-acting hydraulic cylinders, connected between the central movable die part and the movable die part mounted on the movable platen, move the central movable die part into engagement with the movable die part mounted on the movable platen and thereby move a forward surface of the movable die part mounted on the platen into engagement with rear surfaces of the extended cylinder-forming die parts to restrain their rearward movement during casting. The movable platen then carries the movable die parts of the die into a cavity-forming engagement with the stationary die part, and the extended cylinder-forming parts are held in their extended positions, notwithstanding the forces imposed on the cylinder-forming die parts as the cavity is filled with molten metal under extremely high pressures.
Another die example is disclosed in U.S. Pat. No. 6,761,208 (the '208 patent). The V-block casting die disclosed by the '208 patent includes a stationary die part mounted on a stationary platen of a die-casting machine, and only one movable die part mounted on the movable platen of the die-casting machine. The movable die part carries a pair of transversely moving slides that are movable along axes that are generally perpendicular to the direction of movement of the movable platen, and a pair of cylinder-forming die parts that are movable at acute angles along intersecting axes, so that the cylinder-forming die parts may be extended from retracted positions within the movable die part to positions extending within the V-block forming cavity where they may be fitted with sleeves to form the V-block cylinders during casting. In the die disclosed in the '208 patent, the cylinder-forming die parts are locked in their extended positions by locking means carried within the movable die part, and movable into engagement with rear surfaces of the extended cylinder-forming die parts to lock the cylinder-forming die parts in their extended positions, notwithstanding the forces imposed on the cylinder-forming die parts as the cavity is filled with molten metal under extremely high pressures.
Wherever this description refers to cylinder-forming die, or mold, parts or cylinder-forming die core parts, the references refer to those die, or mold, elements that move at an acute angle with respect to the direction of movement of the die casting machine and can carry and position cylinder-forming die, or mold, elements in a V-block casting cavity and/or can carry and position cylinder-forming and water jacket-forming die elements in a V-block casting cavity and can otherwise form the cylinders of a V-block casting.
The '241 and '208 patents disclose two die approaches in use in casting internal combustion engine V-blocks. In both approaches, the movable cylinder-forming die parts of the dies can include two portions. Central cylindrical cylinder-forming die pieces, sometimes referred to mandrels, onto which the sleeves forming the interior surfaces of the cylinders of the internal combustion engine are placed prior to casting, and water jacket-forming die pieces with portions extending adjacent, but spaced from, and frequently at least partially surrounding, the cylinder-forming die pieces, to provide the walls of the internal combustion engine block surrounding its cylinders with coolant passages.
In production, the dies for forming V-block internal combustion engines can produce 20 to 40 blocks per hour, frequently for 24 hours a day, substantially every day of the year. Because of their high use and the high forces, temperatures and pressures to which the dies are exposed, it is not uncommon that they need frequent maintenance, and the repair and replacement of die parts, particularly the cylinder-forming and water jacket-forming die pieces. The forward portions of the water jacket-forming die pieces, for example, can comprise projecting thin wall cylinders which are subjected to the high temperature and high pressure of the molten metal and the high stresses they create within their forwardly extending thin wall cylinder portions, and the water jacket-forming die pieces frequently require repair or replacement if a die assembly is to continue to form acceptable internal combustion engine blocks, and their failures can cause a shut-down in the operation of a V-block die and the manufacture of V-block castings.
Removal of a massive movable die assembly from the die casting machine requires the use of a high-capacity overhead crane. Many engine plants have only one overhead crane with sufficient capacity to lift and move the massive movable die part, which can weigh as much as 90 tons, and the demand for the use of the high-capacity overhead crane can result in long down times in order to repair or replace die parts. Thus, repair and replacement of cylinder-forming die parts and elements can cause lengthy interruptions in the casting and manufacture of internal combustion engine V-blocks.